Co掺杂GaFeO_(3)陶瓷的结构、导电及磁性能研究

Co Incorporation on Structure,Conductivity and Magnetism of GaFeO_(3)

GaFeO_(3)因其磁电耦合效应成为目前极具潜质的多铁性材料之一。本工作采用固相烧结法制备了不同钴掺杂浓度的铁酸镓陶瓷,并研究了钴的掺杂浓度对铁酸镓陶瓷的相组成,微观结构形貌,漏电流及磁性的影响。XRD及Rietveld精修结果显示除了主相GaFeO_(3),还存在第二相,且随着钴含量的增加,第二相含量逐渐增加,晶体的畸变程度增大;因为掺入二价阳离子Co^(2+)并引入了第二相,样品的漏电性能和纯GaFeO_(3)陶瓷相比显著改善;当钴掺杂浓度为2at%时,样品的漏电流密度相较于GaFeO_(3)降低了7个数量级;掺入Co^(2+)引入第二相且晶格畸变程度增加使得GaFeO_(3)的磁性增强。研究结果表明:铁酸镓中掺杂微量的钴可以改善磁性,并使漏电流大幅降低而磁转变温度无明显下降。

GaFeO_(3)is one of the most promising ferromagnetic materials due to its magnetoelectric coupling effect.GaFe1–xCoxO_(3)(x=0,0.02,0.05,0.07,0.10)ceramics were prepared by the conventional solid-state method,and the effect of Co substitution on the microstructure,electrical leakage and magnetic properties was investigated.The XRD patterns and Rietveld refinement using the FullProf package showed that the secondary phase with a Fd3m space group was present in addition to the main GFO phase with a Pc2_(1)n space group,and with an increase of Co doping,the proportion of the secondary phase and the lattice distortion increased.The leakage current density of the GFCO-x samples decreased by approximately 7 orders of magnitude for Co=2 at%.The improved magnetization in GFCO ceramics was attributed to the secondary phase and enhanced lattice distortion.This work suggests that the magnetism was improved by doping Co and the leakage current would be decreased sharply without prominent fluctuation of TC in the meantime by the incorporation of trace amounts of Co.